Fairy Shrimp: All You Need to Know for a Magical Discovery

Fairy shrimp are fascinating aquatic creatures that inhabit temporary freshwater ecosystems, called vernal pools. These intriguing invertebrates showcase unique characteristics, such as a translucent body with colors like blue, green, or orange, depending on factors like age, diet, and the bacterial content of their environment [Field Station].

There are different species of fairy shrimp, including the conservancy fairy shrimp and the vernal pool fairy shrimp, with diverse features that set them apart. For example, male vernal pool fairy shrimp are distinct due to the shape of their second antenna, while the female’s third thoracic segment in the middle part of its body differentiates them from other species [U.S. Fish and Wildlife Service].

What Are Fairy Shrimp

Crustacean Family

Fairy shrimp are small, delicate invertebrates belonging to the branchiopoda crustacean family. They are closely related to other small aquatic creatures such as water fleas and brine shrimp.

Habitats

Fairy shrimp can be found in temporary, fish-free water bodies like vernal pools. They thrive in these environments because they can avoid becoming fish food and escape predation from migrating birds which peak later in the season.

Appearance and Sizes

• Translucent body
• Color ranges from whitish to blue, green, orange, and red
• Size: 0.12 to 1.5 inches (3 to 38 mm) in length
• No hard outer shell

Fairy shrimp exhibit a variety of colors based on their age, diet, and the bacterial content of the water. They differ from other shrimp by lacking a hard outer shell and having distinct antenna shapes.

Fairy shrimp species can be differentiated by specific features such as the male’s second antenna and the female’s third thoracic segment. For example, the vernal pool fairy shrimp and the conservancy fairy shrimp differ in these aspects.

Life Cycle and Reproduction

Eggs and Cysts

Fairy shrimp produce eggs called cysts. The cysts are highly resistant and can remain dormant for years, allowing them to survive unfavorable environmental conditions. Some features of fairy shrimp cysts include:

• Dormancy: Withstands extreme temperatures and drying
• Hatching: Hatches when environmental conditions are favorable
• Longevity: Can remain viable for multiple years

Hatching and Development

After hatching, fairy shrimp start their development as larvae called berra. They undergo a series of molts, gradually increasing in size. The development involves:

• Multiple stages: Fairy shrimp pass through several growth stages before reaching maturity
• Growth: Rapid growth occurs within a few weeks
• Mating: Maturity is reached and mating occurs between males and females

A comparison of two common fairy shrimp species’ development times:

Lifespan

Fairy shrimp have a relatively short lifespan, which varies depending on the species. For example, the vernal pool fairy shrimp lives for an average of 91 days. They begin their life in vernal pools around November and complete their life cycle by early May.

Feeding and Nutrition

Filter Feeders

Fairy shrimp are filter feeders, using their legs to create water currents that help them capture food particles. They have the following features:

• Well-adapted to their vernal pool habitats
• Efficiently consume small particles in the water
• Contribute to maintaining water quality

Diet Components

Fairy shrimp primarily consume the following:

• Algae: A primary food source in vernal pools
• Bacteria: Microscopic organisms present in their habitat
• Protozoa: Single-celled organisms that float in the water
• Detritus: Decaying organic matter, like fallen leaves and dead insects

Feeding in Captivity

Feeding fairy shrimp in captivity requires replicating their natural diet as closely as possible. To do this, use the following:

• Yeast soup: A mixture of yeast, sugar, and water
• Fish food flakes: Crushed to a fine powder
• Eyedropper or pipette: To carefully administer the food

Pros:

• Maintains the health and vitality of captive fairy shrimp
• Can stimulate the growth and hatching of dormant cysts

Cons:

• Requires close monitoring of the water temperature and light conditions
• May not completely replicate the breadth of their natural diet

Habitats and Distribution

Vernal Pools

Fairy shrimp inhabit seasonal vernal pools, where they live in shallow, fish-free water¹. These temporary water bodies provide a unique ecosystem that helps fairy shrimp avoid predators such as fish and migratory birds². Vernal pools are rich habitats for various types of grasses and other aquatic organisms, contributing to the overall ecology of the region.

Location and Range

Fairy shrimp are mainly found in specific regions of California, Oregon, and other parts of the United States. Some notable areas include:

• Central Valley
• Tehama County
• Merced County
• Ventura County³

The vernal pool ecosystems in areas such as Vina Plains, Glenn County, Solano County, and Stanislaus County are also home to a diverse range of fairy shrimp species⁴.

Threats and Conservation

Fairy shrimp face several threats, primarily due to habitat loss from factors like:

• Agriculture
• Urban development
• Drought

As a result, some fairy shrimp species, such as Branchinecta conservatio, become endangered or threatened. Conservation efforts are ongoing, involving collaborations between organizations like the University of California and the government to protect habitats like the Grasslands Ecological Area and the Los Padres National Forest⁵.

With these conservation efforts in place, it is hoped that the unique habitats and ecosystems supporting fairy shrimp and other organisms can continue to thrive and contribute to the overall biodiversity of the region.

Fairy Shrimp as Pets

Housing and Tank Setup

Fairy shrimp are small crustaceans that thrive in temporary water bodies, like vernal pools. To create a suitable environment for these pets:

• Use a spacious container or aquarium
• Mimic their natural habitat with a substrate of soil, pebbles, or sand
• Add aquatic vegetation and leaf litter as hiding spots
• Ensure minimal water flow in the tank

Water Conditions and Maintenance

Fairy shrimp can adapt to a variety of water conditions, but certain parameters must be maintained:

• Maintain water temperatures between 10 and 22°C (50-72°F)
• Keep water salinity low, as they cannot tolerate high salt concentrations
• Replace water partially every few days, or add aged water to maintain the tank’s balance
• Avoid using water with chlorine, as it is harmful to fairy shrimp
• Regularly check the overall health of your shrimp and monitor ammonia and nitrite levels in the water

Feeding and Care Tips

In the wild, fairy shrimp mostly feed on algae, bacteria, and microorganisms like rotifers. Here are some key feeding tips:

• Purchase specialty fairy shrimp foods or use powdered algae and yeast as an alternative
• Feed them small amounts several times a day to ensure optimal growth
• Monitor their population to avoid overcrowding, as fairy shrimp can reproduce rapidly
• Observe your shrimp’s behavior and adjust their diet accordingly if they appear stressed or unhealthy

It’s essential to note that certain species of fairy shrimp are endangered. Keeping them in captivity might be subject to legal restrictions. Research and comply with local regulations before acquiring these fascinating aquatic pets.

Interesting Facts and Species

Endangered and Threatened Species

The Fairy Shrimp have a few species that are considered endangered or threatened. Some examples of these species include the Vernal Pool Fairy Shrimp and the Conservancy Fairy Shrimp. These species are often found in vernal pools and their habitats are protected by organizations like The Nature Conservancy.

Unique Characteristics

• Translucent body
• Color varies based on factors like age, diet, and water conditions
• No hard outer shell like other shrimp species
• Inhabit fish-free vernal pools to avoid predators
• Sensitive to water conditions like alkalinity and chlorine

Fairy Shrimp are fascinating creatures due to their unique characteristics. They are translucent and exhibit different colors based on factors such as age, diet, and bacterial content of the water. Unlike other shrimp species, these crustaceans do not have a hard outer shell. They thrive in fish-free vernal pools which allow them to avoid predators. Moreover, Fairy Shrimp are sensitive to changes in water conditions like alkalinity and chlorine levels.

Notable Examples

Vernal Pool Fairy Shrimp (Branchinecta lynchi)

• Measures 0.12 to 1.5 inches in length
• Distinct shape of the male’s second antenna
• Unique third thoracic segment shape in females

Conservancy Fairy Shrimp (Branchinecta conservatio)

• Found only in California’s Central Valley region
• Restricted to vernal pools from Tehama County to Merced County
• Named for The Nature Conservancy organization

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – Fairy Shrimp

Swimming insect?fish?
September 21, 2009
I found hundreds of these swimming in a small man made lake in the backyard of my home in Winnipeg Manitoba, no one can seem to tell me what they are.
I have tried other identifying sites before but never seem to get a reply. They were out swimming around the beginning of summer. They seem to swim by fluttering the green fleshy/gill like stuff on their back. I also noticed that some of them had what looked like long egg sacks running along the top of their backs. Can someone please tell me what these are?
Carly
Winnipeg Manitoba

Hi Carly,
First we need to say that we went back through the past week’s mail to try to answer a few additional questions when we stumbled upon your letter.  We are very excited to post your images of Fairy Shrimp, freshwater crustaceans.  Fairy Shrimp often live in ponds that dry up, and their eggs are laid and eventually dry in the mud when the water evaporates.  Then the next spring, the temporary pond fills with water again and the eggs hatch, beginning a new cycle.  We have never seen green Fairy Shrimp, and in a few minutes, we are going to try to research something more specific for you.  In our childhood home of Ohio, we would catch Fairy Shrimp in March and April, so we find your September sighting unusual.  You also didn’t indicate if the lake dries out.  The one site we found in a brief search indicates vernal pools as the typical habitat, and none of the images show green Fairy Shrimp.

Letter 2 – Fairy Shrimp

please tell us what this is
the kids and i went for a walk and thought we saw minnows swimming around in swamp near home.when we looked closer found out it was some kind of larvae . can you tell us what this is? it swims on its back i think?
Steve

Hi Steve,
Fairy Shrimp are Crustaceans that are usually found in the spring in ponds that dry up in the summer. Eggs are laid and wait in the dry mud for spring rains or winter thaws before they hatch. They are relatede to Sea Monkeys.

Letter 3 – Fairy Shrimp

Subject:  Images of Fairy Shrimp
Geographic location of the bug:  Florida
Date: 08/25/2019
Time: 02:05 PM EDT
Your letter to the bugman:  I never knew fairy shrimps even existed in Florida- and seeing these in a vernal pool near my school made me so, so excited! They are my favorite invertebrates on this earth(just look at their cute little eyes, awww), and I felt like i needed to share a little bit of my joy with you!
How you want your letter signed:  Chance Arceneaux, Fairy Shrimp Fanatic

Dear Chance,
We share your enthusiasm.  Daniel first discovered Fairy Shrimp over 50 years ago in a vernal pond in Northeast Ohio, and when a funeral home was built on the site of the pond that also provided a home for tadpoles and numerous aquatic insects, it was probably his first experience with the loss of open space due to development, a cause for which he remains dedicated to oppose.  Daniel was quite excited when he discovered Fairy Shrimp in a vernal pond near the L.A. River in 2010.  We wish you had submitted larger digital files of your images as the quality was somewhat degraded when we formatted the low resolution files for posting.  BugGuide includes Florida among the locations where Fairy Shrimp have been sighted and reported.

Letter 4 – Fairy Shrimp

Subject:  More images of Fairy Shrimp
Geographic location of the bug:  Florida, St. Petersburg
Date: 08/31/2019
Time: 12:46 PM EDT
Your letter to the bugman:  I know i’ve sent fairy shrimp images before, but those were pretty low-quality(sorry about that), so I took some more images!
Some aquarium equipment is visible in the images because i’m trying my hand at raising them- so far so good, they’re comfortable enough to reproduce(it isn’t a very romantic affair…)
All these images are females, as they have their brood pouches full, still awaiting the day where i notice one depositing eggs…..
I still love fairy shrimps more than ever and i’m super happy that i’m able to submit these images, fairy shrimp go largely unappreciated on the internet!
How you want your letter signed:  Chance Arceneaux

Dear Chance,
Thanks for submitting new images of your Fairy Shrimp as well as information about raising them in captivity.  As we requested in our response to your previous submission of Fairy Shrimp:  ” We wish you had submitted larger digital files of your images as the quality was somewhat degraded when we formatted the low resolution files for posting.”  Once again we had to increase the size of your 300×400 pixel png file to convert it to a 550×800 pixel jpg.  Please do not reduce the file of your images in the future.  We would much rather decrease the file size of a larger image than to increase the file size which leads to image degradation.